Mixing and comminuting apparatus

ABSTRACT

An agitator and cutter assembly for a food blender and the like having cutter blades arranged so that they may be tilted from a vertical axis to change the pitch of the blades.

United States Patent 1 1 1 1 9 9 18 Hurwitz Jan. 8, 1974 [54] MIXING ANDCOMMINUTING APPARATU 2,577,802 12/1951 Payne 259/108 3 156 278 11/1964 Otto 241/2822 [76] Inventor: Mathew Hurwitz 63 Oakland Ave., 2 9 1O ubu a e ss 02166 3,493,215 2/1970 Edwards et al. 5 8

[22] Filed: 1972 Primary ExaminerGranville Y Custer, Jr. 1211 pp 224,111 4 14E liaqmir r tfiar N;9 9b

Attorney-Nathan N. Kraus, Joseph R. Marcus and [52 US. Cl 241/282.1, 259/108 Gerald [51] Int. Cl. B02c 18/12 [58] Field of Search 24l/l99.l2, 277, V

241/2821, 282.2, 46.17; 259/107, 108, DIG. [57] ABSTRACT 26; 209/169 An agitator and cutter assembly for a food blender and the like having cutter blades arranged So that they [56] References Cited may be tilted from a vertical axis to change the pitch UNITED STATES PATENTS of the blades.

2,239,194 4/1941 Fitzgerald et al. 209/169 X 16 Claims, 20 Drawing Figures F 1 5/ 5; 47 I 5/ 3 I 46 l L 30 ll 6 2a Z3 1 as l 1 5-."- I h I ll m .1 1 58 Q i PATENTEU JAN 8 4 SHEET 2 BF 3 FIG, 621

FIG, 5 a

FIG, 3

PEG, 7

PATENTED JAN 8 I974 SHEET 3 BF 3 1 MIXING AND COMMINUTING APPARATUS FIELD OF THE INVENTION The present invention relates to an apparatus for BACKGROUND OF THE INVENTION A common objectionable condition found in many prior art blenders is the tendency of certain kinds of foods being processed to bridge over the agitator blades because of self-impeded circulation which hinders the desired vortex-like flow of unchopped food to the blades and of chopped food away from the blades. The result is that a small portion of the food being processed may become overblended, mushy or too finely comminuted with the major portion of the food remaining substantially unprocessed. In order to alleviate this condition common expedients are to vary the blender speed, to switch the blender on and off periodically, or to use a spatula or like implement manually to stir or. force food towards the agitator blades. Also, some improved blade configurations have somewhat remedied the problem with certain foods but, for the most part, the improvements seen with some foods are paid for at the expense of either a degradation in performance with other foods or a gross overloading of the blender motor when highly viscous foods or other materials are processed. In particular, it is well known that few food blenders are capable of producing consistently acceptable coarse chopped foods, such as cole slaw, egg salad, grated cheese, celery, nuts, graham cracker crumbs, carrots, and the like. Most blenders commonly produce a puree of too finely comminuted food or a paste when what was desired was a coarse chopped consistency similar to what might be obtained using a food grater or meat grinder. In many cases, the user becomes disillusioned and abandons any further attempt at using the blender for such foods. Thus, too many blenders become relegated to the trivial operation of mixing only liquids.

SUMMARY OF THE INVENTION It is an object of the present invention to provide an improved agitator-cutter assembly having means by which the user may conveniently adjust the angular disposition or pitch of the agitator blades relative to their axis of rotation to produce varying degrees of dynamic v coupling between the blades and the food, as may be required by the various foods.

Another object of this invention is the provision of means for safely and conveniently adjusting blade pitch with the agitator and blender jar assembled but removed from the blender motor base.

Still another object of this invention is the provision of agitator blades having a novel configuration which may be utilized in fixed or adjustable pitch modes. These blades have been found to afford significant improvements in performance even when operated with conventional blender agitators which lack any adjustable pitch feature.

A further object of this invention is the provision of an improved agitator-cutter assembly and cooperative means by which the user may safely and conveniently adjust the pitch of the blades while the agitator and blender jar remain mounted on the blender motor base.

Still a further object of this invention is the provision of an apparatus of the foregoing type which may be produced competitively with certain costly multi-speed blenders available on the market, since the use of adjustable pitch blades, in accordance with my invention, will enable a blender having one or two or at the most three speeds, to outperform a multi-speed apparatus of corresponding power.

Other and further objects and advantages of my invention will become apparent as the following description of preferred embodiments proceeds and the features of novelty which characterize the invention will be pointed out with particularity in the appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a vertical cross-sectional view of an agitatorcutter assembly having a single cutter blade,.in accordance with my invention.

FIG. 2 is a similar view of a modified embodiment provided with two cutter blades.

FIG. 3 is a perspective view of one embodiment of an agitator-cutter blade unit, in accordance with my invention.

FIG. 4 is a similar view of another embodiment of an agitator-cutter blade unit.

FIG. 5 is a top plan view of a coupling element, on an enlarged scale.

FIG. 5a is a cross-sectional view taken substantially on line 5a5a of FIG. 5.

FIG. 6 is a plan view ofa modified embodiment of the coupling element shown in FIG. 5.

FIG. 6a is a cross-sectional view taken substantially on line 6a6a of FIG. 6.

FIG. 7 is a perspective view of a well known blender apparatus embodying one form of my invention.

FIG. 8 is a similar view of another embodiment of my invention which permits manual adjustment of the pitch of the agitator blades, while the blender jar is on the base.

FIG. 9 is a similar view of another modified embodiment wherein adjustment of the pitch of the agitator blades is effected by reversing the direction of rotation of the blender motor.

FIG. 10 is a bottom plan view, partly in cross section and on a reduced scale, of the agitator and jar nut illustrated in FIGS. 1 and 2.

FIG. 11 is a bottom plan view of a detail illustrated in FIG. 1

FIG. 12 is a bottom plan view of a modified embodiment of the detail illustrated in FIG. 11.

FIG. 13 is a top plan view of a blank of one embodiment of a cutter blade shown in FIG. 4.

FIG. 14 is a side elevational view thereof showing in broken lines the final configuration of the cutter blade.

FIG. 15 is an end elevational view of the cutter blade illustrated in FIGS. 13 and 14 in its final configuration.

FIG. 16 is a view similar to FIG. 13 ofa modified embodiment of cutter blade.

FIG. 17 is a view similar to FIG. 14 of the modified embodiment illustrated in FIG. 16, and,

FIG. 18 is a view similar to FIG. 15 of the modified embodiment illustrated in FIG. 16.

BRIEF DESCRIPTION OF A PREFERRED EMBODIMENT Referring particularly to FIG. 1 of the drawings, the numeral 20 indicates generally an agitator-cutter and jar nut assembly which is arranged to be threaded to the lower end of a container 200 in a conventional manner. The jar nut 21 basically is an annular member formed preferably of molded plastic having vertical ribs 25 to facilitate handling and provided with internal threads 23 and an inwardly directed integral flange 24. Rested on the flange 24 is a support disc 26 having an annular offset portion and provided with a central aperture in which is received a generally tubular shaft housing 27, the housing being secured to the disc 26 as by swaging or welding. The offset portion supports a gasket 201 which seals the assembly 20 to the blender jar 200. A hollow shaft 28 is rotatable in a bushing 29 press fitted in the housing 27. An annular wedge shaped disc 31 having a lower face normal to the axis of the disc and an upper face in non-parallel relationship to the lower face, preferably at an acute angle a of approximately 8l2 to the plane of the lower face, is suitably secured as by swaging or welding to the upper end of the shaft 28. A thrust washer/slinger 32, cup-shaped, substantially as illustrated in FIG. 1, rests on top of the bushing 29. Compressed between the disc 31 and slinger 32 is a ring 30 of elastomeric material which functions both as a seal to prevent the ingress of any fluid or solid material into the clearance space between the shaft 28 and bushing 29 and as a spring to provide a desired preloading on the washer 32. Suitably secured to the lower end of the shaft 28 is an adjuster disc 33, shaped substantially as illustrated. Said disc may be provided with knurls 34 on its periphery (FIGS. 10 and 11). A pair of diametrically opposed drive dogs 36 (FIG. 1 l) are integral with the under surface of the adjuster disc 33 and function, as will be hereinafter explained. It will be noted that the adjuster disc 33, shaft 28 and disc 31 are in fixed relationship and rotate as a unit.

A drive shaft 37 is rotatably supported within the shaft 28 and has an enlarged lower end which is pressed into the metal core 39 of a drive coupling, indicated generally by the numeral 38, (FIGS. and 5a), said metal core having on its upper surface opposed shoulders 41 adjacent to respective ratchet ramps 42 (FIGS. 5 and 5a). The dogs 36 of the adjuster disc 33 (FIG. 11) cooperate with the shoulders 41, as will be hereinafter explained. Fixed to the'underside of the core 39 may be a rubber coupling element 44a (FIGv of conventional construction which comprises a plurality of depending fingers arranged to interengage with similar fingers of a cooperating coupling element carried on the motor drive shaft of the blender base. Alternatively, an eight pointed star shaped socket 44b may be provided in the enlarged end of shaft 37 (FIG. 10) to enable the shaft to couple to blender-s having square drive couplings. The upper end of the shaft 37 is provided with a pair of diametrically opposed milled flats 46. An agitator-cutter blade indicated generally by the numeral 48 and hereinafter to be described in greater detail, is rested on the wedge disc 31 and is surmounted by an elastomeric washer 49 and a flat washer 51, all secured by upsetting the reduced end portion of shaft 37 as at 47. The elastomeric washer 49 functions both as a seal to prevent foreign matter from entering into the clearance area between the shafts 37 and 28 and as a spring for providing an axialpreload so that the cooperating drive elements of the adjuster disc 33 and coupling 38 are maintained in interengagement.

The cutter 48 (FIGS. 4, 13-15) includes a central hub portion 50 and oppositely disposed integral blades 51. The hub portion 50 is provided with a centrally located rectangular slot 53 in which is received the milled portion of the shaft 37. Thus, the cutter 48 is keyed to rotate with the shaft 37 but because the slot is oversized it is capable of being tilted angularly relative to the shaft axis, as will be hereinafter made clear. The blades 51 are generally triangular in form and connected by intermediate portions 51a to the hub portion 5%. One blade 51 extends upwardly in a plane disposed typically at an angle of 45 to the plane of the hub portion 50. The other blade 51 extends downwardly in a plane disposed typically at an angle of 60 in relation to the plane of the hub portion 50. Each of the blades 51 includes compound bends (FIGS. 4, 13-15). The upwardly directed blade is first bent along line a at an angle of substantially and then is bent outwardly along line b at an angle of substantially 45. The two bend lines a and b are at an angle ,8 relative to each other, said angle typically having a value of approximately 8-12. Similarly, the downwardly directed blade is bent down 90 along line a and outwardly approximately 30 along line b.

In accordance with my invention, the cutter 48 may be operated in two distinct attitudes or positions relative to the axis of rotation in order to effect a change in the pitch of the blades in relation to the axis of rotation. For example, in a first position of the cutter 48, the angle B is added to the wedge angle a of the disc 31 with the result that the blades 51 assume a first an gular relationship with the axis of rotation based on the sum of angles a and B. In a second position, wherein the position of the cutter 48 is rotated the angle a is subtracted from angle B of the wedge disc 31 with the result that the blades 51 assume a second angular relationship with the axis of rotation based on the difference between angles oz and [3. Thus, in accordance with my invention the pitch of the blades may be changed to achieve different operational effects.

It will be understood that relative movement in the direction counter to powered rotation between shaft 37 and hollow shaft 28 is permitted. In powered operation the dogs 36 of adjuster disc 33 engage against the shoulders 41 of core 39 and effect simultaneous rotation of these two parts so that disc 31 and shaft 37 rotate together. In order to effect a change in the pitch of the blades 51, the drive coupling 38 is manually or otherwise rotated 180 in a reverse direction while the adjuster disc 33 is held stationary, as will be presently described. It will be apparent that in such reverse rotation the dogs 36 will disengage from the shoulders 41, ride over the ratchet ramps 42 and the adjacent surfaces 39a of the coupling core 39 and snap into engagement with opposed ratchet ramps 42 so that when the coupling element 38 is again driven in a forward direction the dogs 36 will engage with opposite shoulders 41. The blades 51 are now in a different angular relation to the axis of shaft 37 and in rotation they will produce an effect on the materials being processed in the blender apparatus different from that produced when the blades are disposed in the position first described. This results in a significant improvement in performance and extends the usefulness of the blender apparatus by enabling it to perform operations heretofore either not possible or impracticable. Specifically, in the higher pitch mode the blades are particularly well disposed for coarse chopping whereas in the lower pitch mode the blades are appropriately disposed for blending viscous fluids without overloading the blender motor.

Although, as was hereinabove explained, the adjuster disc 33 may be manually grasped at the knurls 34 and held in a stationary position while the drive coupling 38 is being rotated, I have provided means associated with the jar nut 21 to facilitate the foregoing adjustment. Referring to FIG. 1 an elastomeric brake ring 56 is disposed in the lower part of the jar nut 21 concentric with the adjuster disc 33 and substantially in horizontal registration with the knurls 34, the brake ring 56 being retained in position by a snap ring 57. The brake ring 56 is provided with a plurality of buttons 58 which project radially outwardly through openings in the wall of the jar nut 21. Adequate clearance is provided between the brake ring 56 and adjuster disc 33 so that the disc will not rub against the ring in normal operation. In order to hold the adjuster disc 33 stationary the operator is required merely to press against a button 58 which ef fects deformation of the brake ring 56 and causes an inner portion thereof to engage against the knurls 34, thereby holding the adjuster disc stationary so that the drive coupling 38 may be manually rotated 180 to effect a change in the pitch of the blades.

The modified embodiment of my invention illustrated in FIG. 2 utilizes a pair of cutters instead of the single cutter of the embodiment of FIG. 1. For purposes of simplification the parts which are common to both embodiments will be identified by corresponding numerals.

A lower cutter 93, of generally conventional construction, and wedge disc 31 are fixed to the hollow shaft 28 as by pressing swaging or welding to form an integrated unit. The upper cutter 105, formed substantially as illustrated in FIG. 3, includes a hub portion 108 having a rectangular drive slot 109 and upwardly directed integral blades 111, presently to be described. The upper cutter 105 includes compound bends substantially similar to those of cutter 48, hereinabove described. Specifically, the cutter 105 is formed of a blank 107 (FIG. 16). The blades 111 are first bent upwardly along lines 0 relative to the plane of hub portion 108 and then outwardly along lines d at an angle of substantially 45 relative to the axis of rotation (FIG. 17). Similarly, as in the blade 48 the bend lines 0 and a' are disposed at an angle B (FIG. 18) relative to each other. It will be apparent that the wedge disc 31 and cutter 105 cooperate in the same manner, hereinbefore described, to vary the pitch of the blades 111. The blades 11] may be alternately tilted or pitched relative to the axis of rotation to either of two positions, one position being determined by the sum of the angles a and B and the other by the difference of the two angles, depending upon the relative positions of the drive elements on the adjuster disc 33 and drive core 39.

My invention contemplates the use of suitable mechanical means for effecting a change in pitch of the blades while the apparatus is in use. FIG. 7 illustrates one embodiment, probably the most simple form hereinabove referred to, whereby the jar 200 and agitator assembly are removed from the base 121 when it is desired to change the pitch of the blades. Adjustment is manual, the same being effected by the user pressing against one or more of the brake ring buttons 58 with one hand while reversely rotating the drive coupling 38 with the other hand.

In FIG. 8 there is shown an embodiment incorporating the features of the invention in which the base 121 of the apparatus includes a pair of levers 122 and 123 which project outwardly of a slot 124, the said slot extending substantially half-way around the circumference of the base 121 and terminating substantially at diametrically opposite points. Levers 122 and 123 may be connected, by appropriate means, not shown, to respectively engage the adjuster disc 33 and drive coupling 38 to secure either one of said parts against rotation while effecting rotation of the cooperating part approximately one-half turn so as to dispose the blades in a different relation, thereby to effect a change in the pitch of the blades. It is considered that the means available for accomplishing the foregoing result are clearly within the scope of one skilled in the art and would not require the exercise of invention to construct such mechanism. It will be understood that in this embodiment either of the combinations of the cores and adjuster discs, hereinabove described, could be employed.

FIG. 9 illustrates another embodiment in which the blender base 121a utilizes a motor which may be operated in two directions, forward and reverse, the motor being controlled by button operated switches 126 and 127. In this embodiment the agitator cutter blades are sharpened along both edges so that they are operative in either direction of rotation. This embodiment re quires a modified coupling core 101 (FIGS. 6 and 6a) and adjuster disc 33a (FIG. 12). The core 101 includes a pair of diametrically disposed radial drive dogs 116a and 1 16b which engage with similar drive dogs 36a and 36b on the underside of adjuster disc 33a. This arrangement provides nearly of backlash between the coupling core 101 and the adjuster disc 330. An annular shoulder 117 on core 101 affords a bearing surface in engagement with the underside of adjuster disc 33a. Accordingly, when the blender motor is driven in a forward direction the dogs 116a and 1l6b engage dogs 36a and 36b respectively. When the motor is driven in a reverse direction the dogs 116a and 11612 are caused to engage dogs 36b and 36a respectively, and shaft 37 moves about 180 relative to shaft 28. Accordingly, during forward rotation of the motor the blades 51 or 111 will be pitched at one angle relative to the axis of rotation and during reverse rotation, the blades will be automatically adjusted to a second pitch angle different from the first described position.

It will also be understood that my invention contemplates various combinations utilizing the different cutter arrangements, hereinabove described, with the different means for effecting a change in blade pitch.

Various changes coming within the spirit of my invention may suggest themselves to those skilled in the art; hence, I do not wish to be limited to the specific embodiments shown and described or uses mentioned, but intend the same to be merely exemplary, the scope of my invention being limited only by the appended claims.

I claim:

1. In an agitator and cutter assembly for a blending and comminuting apparatus a one piece rotary cutter including a hub portion and extending blades having a fixed angular relationship to each other and means for tilting said cutter at an angle relative to its axis of rotation for varying the attitude of said blades.

2. In an agitator and cutter assembly for a blending and comminuting apparatus, a drive shaft, a cutter having extending blades and keyed to said shaft for rotation therewith but being tiltably movable axially thereof, and cam means rotatably movable relative to said shaft and engageable with said cutter to vary the angular disposition of said cutter thereby to vary the pitch of said blades.

3. An agitator and cutter assembly for a blending and comminuting apparatus comprising a drive coupling arranged to be connected to power drive means, a drive shaft fixed to said coupling, a cutter having extending blades and keyed to said drive shaft for rotation therewith but being tiltably movable relative to the axis thereof, a hollow shaft concentric with said drive shaft and rotatably receiving said drive shaft, a wedge shaped member fixed to the upper end of said upper shaft, the

upper face of said member being disposed in a plane angular to a plane normal to the axis of said drive shaft, said cutter resting on said upper face of said member, an adjuster member rigid with the lower end of said hollow shaft and having a surface in abutment with a confronting surface of said drive coupling, the adjuster member being rotatable relative to said drive coupling, and resilient means urging said cutter into engagement with said upper face, said cutter being rotatably movable relative to said upper face whereby to vary the angular disposition of said blades relative to their axis of rotation thereby to vary the pitch of said blades.

4. The invention as defined in claim 3 including a second cutter fixed to said hollow shaft.

5. The invention as defined in claim 3 in which the resilient means comprises an elastomeric washer.

6. The invention as defined in claim 3 in which the abutting surfaces of said adjuster member and said drive coupling are provided with interengaging shoul ders to effect a driving connection therebetween.

7. The invention as defined in claim 3 including braking means for arresting movement of said adjuster member while manually rotating said drive coupling to move said cutter relative to said wedge shaped memher.

8. The invention as defined in claim 3 including braking means for arresting movement of said adjuster member while the drive coupling is being rotated to move said cutter relative to said adjuster member thereby to adjust the position of the cutter relative to the wedge shaped member.

9. The invention as defined in claim 3 including braking means comprising a deformable elastomeric ring concentric with said adjuster member.

10. The invention as defined in claim 3 in which the root line of each of the blades is disposed at an angle substantially similar to the angle of the wedge shaped member.

11. The invention as defined in claim 3 in which the abutting surfaces of the adjuster member and the drive coupling include cooperating ratchet elements to afford relative movement between the adjuster member and the drive coupling in one direction of rotation.

12. In an agitator and cutter assembly for a blending and comminuting apparatus, a drive shaft, a cutter having a hub portion having a central slot and extending blades and being keyed to said shaft for rotation therewith but being tiltably movable relative to the axis of the shaft, each of said blades being compoundly bent in angular relation to the plane of said hub portion and being connected to said hub portion by an intermediate portion substantially normal to the plane of the hub portion, the root line of each of said blades at the juncture of said intermediate portion and the base of the blade being disposed in angular relation to the plane of said hub portion.

13. The invention as defined in claim 12 including means for tilting said cutter to vary the pitch of said blades relative to their axis of rotation.

14. A blending and comminuting apparatus comprising in combination an agitator cutter assembly having a drive shaft, a cutter having extending blades and keyed to said shaft for rotation therewith but being tiltably movable axially thereof, cam means rotatably movable relative to said shaft and engageable with said cutter to vary the tilt of said cutter thereby to vary the pitch of said blades, a reversible motor for driving said shaft, and means for changing the direction of rotation of said motor to effect relative movement between said shaft and said cam means thereby to adjust the pitch of said blades.

15. The invention as defined in claim 14 including coupling means interposed between said shaft and said cam means and permitting substantially relative rotation in either direction between said shaft and said cam means.

16. The invention as defined in claim 2 in which the cam means comprises a wedge shaped disc. 

1. In an agitator and cutter assembly for a blending and comminuting apparatus a one piece rotary cutter including a hub portion and extending blades having a fixed angular relationship to each other and means for tilting said cutter at an angle relative to its axis of rotation for varying the attitude of said blades.
 2. In an agitator and cutter assembly for a blending and comminuting apparatus, a drive shaft, a cutter having extending blades and keyed to said shaft for rotation therewith but being tiltably movable axially thereof, and cam means rotatably movable relative to said shaft and engageable with said cutter to vary the angular disposition of said cutter thereby to vary the pitch of said blades.
 3. An agitator and cutter assembly for a blending and comminuting apparatus comprising a drive coupling arranged to be connected to power drive means, a drive shaft fixed to said coupling, a cutter having extending blades and keyed to said drive shaft for rotation therewith but being tiltably movable relative to the axis thereof, a hollow shaft concentric with said drive shaft and rotatably receiving said drive shaft, a wedge shaped member fixed to the upper end of said upper shaft, the upper face of said member being disposed in a plane angular to a plane normal to the axis of said drive shaft, said cutter resting on said upper face of said member, an adjuster member rigid with the lower end of said hollow shaft and having a surface in abutment with a confronting surface of said drive coupling, the adjuster member being rotatable relative to said drive coupling, and resilient means urging said cutter into engagement with said upper face, said cutter being rotatably movable relative to said upper face whereby to vary the angular disposition of said blades relative to their axis of rotation thereby to vary the pitch of said blades.
 4. The invention as defined in claim 3 including a second cutter fixed to said hollow shaft.
 5. The invention as defined in claim 3 in which the resilient means comprises an elastomeric washer.
 6. The invention as defined in claim 3 in which the abutting surfaces of said adjuster member and said drive coupling are provided with interengaging shoulders to effect a driving connection therebetween.
 7. The invention as defined in claim 3 including braking means for arresting movement of said adjuster member while manually rotating said drive coupling to move said cutter relative to said wedge shaped member.
 8. The invention as defined in claim 3 including braking means for arresting movement of said adjuster member while the drive coupling is being rotated to move said cutter relative to said adjuster member thereby to adjust the posItion of the cutter relative to the wedge shaped member.
 9. The invention as defined in claim 3 including braking means comprising a deformable elastomeric ring concentric with said adjuster member.
 10. The invention as defined in claim 3 in which the root line of each of the blades is disposed at an angle substantially similar to the angle of the wedge shaped member.
 11. The invention as defined in claim 3 in which the abutting surfaces of the adjuster member and the drive coupling include cooperating ratchet elements to afford relative movement between the adjuster member and the drive coupling in one direction of rotation.
 12. In an agitator and cutter assembly for a blending and comminuting apparatus, a drive shaft, a cutter having a hub portion having a central slot and extending blades and being keyed to said shaft for rotation therewith but being tiltably movable relative to the axis of the shaft, each of said blades being compoundly bent in angular relation to the plane of said hub portion and being connected to said hub portion by an intermediate portion substantially normal to the plane of the hub portion, the root line of each of said blades at the juncture of said intermediate portion and the base of the blade being disposed in angular relation to the plane of said hub portion.
 13. The invention as defined in claim 12 including means for tilting said cutter to vary the pitch of said blades relative to their axis of rotation.
 14. A blending and comminuting apparatus comprising in combination an agitator cutter assembly having a drive shaft, a cutter having extending blades and keyed to said shaft for rotation therewith but being tiltably movable axially thereof, cam means rotatably movable relative to said shaft and engageable with said cutter to vary the tilt of said cutter thereby to vary the pitch of said blades, a reversible motor for driving said shaft, and means for changing the direction of rotation of said motor to effect relative movement between said shaft and said cam means thereby to adjust the pitch of said blades.
 15. The invention as defined in claim 14 including coupling means interposed between said shaft and said cam means and permitting substantially 180* relative rotation in either direction between said shaft and said cam means.
 16. The invention as defined in claim 2 in which the cam means comprises a wedge shaped disc. 